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Human-modified Landscapes (human-modified + landscapes)
Selected AbstractsThe Potential for Species Conservation in Tropical Secondary ForestsCONSERVATION BIOLOGY, Issue 6 2009ROBIN L. CHAZDON especialización de hábitat; biodiversidad forestal; bosque secundario; bosque tropical; sucesión Abstract:,In the wake of widespread loss of old-growth forests throughout the tropics, secondary forests will likely play a growing role in the conservation of forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary forests. Beyond the characteristics of local forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary forests. Prospects for conservation of old-growth species in secondary forests are maximized in regions where the ratio of secondary to old-growth forest area is relatively low, older secondary forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed-dispersing fauna are present, and old-growth forests are close to abandoned sites. The conservation value of a secondary forest is expected to increase over time, as species arriving from remaining old-growth forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of old-growth species present in secondary forests. Older secondary forests are not often studied and few long-term studies are conducted in secondary forests. Available data indicate that both old-growth and second-growth forests are important to the persistence of forest species in tropical, human-modified landscapes. Resumen:,A raíz de la pérdida generalizada de los bosques maduros en el trópico, los bosques secundarios probablemente jugarán un mayor papel en la conservación de la biodiversidad forestal. Consideramos una jerarquía compleja de factores que interactúan en el espacio y tiempo para determinar el potencial de conservación de los bosques tropicales secundarios. Más allá de las características de los fragmentos de bosque locales, la dinámica espacial y temporal del paisaje influye en el establecimiento, la composición de especies y la persistencia de bosques secundarios. Los prospectos para la conservación de especies primarias en los bosques secundarios se maximizan en regiones donde la proporción de superficie de bosque maduro-bosque secundario es relativamente baja, los bosques secundarios más viejos han persistido, la perturbación antropogénica después del abandono es relativamente baja, hay presencia de fauna dispersora de semillas y donde hay bosques primarios cerca de sitios abandonados. Se espera que el valor de conservación de un bosque secundario incremente en el tiempo, a medida que se acumulan especies provenientes de los fragmentos de bosque primario remanentes. Muchos estudios están pobremente replicados, lo que impide evaluaciones robustas del número y abundancia de especies primarias presentes en bosques secundarios. Los bosques secundarios más viejos generalmente no son estudiados y son pocos los estudios a largo plazo en bosques secundarios. Los datos disponibles indican que tanto los bosques primarios como los secundarios son importantes para la persistencia de especies forestales en paisajes tropicales modificados por humanos. [source] Non-optimal animal movement in human-altered landscapesFUNCTIONAL ECOLOGY, Issue 6 2007LENORE FAHRIG Summary 1I synthesize the understanding of the relationship between landscape structure and animal movement in human-modified landscapes. 2The variety of landscape structures is first classified into four categories: continuous habitat, patchy habitat with high-quality matrix, patchy habitat with low-quality matrix, and patchy, ephemeral habitat. Using this simplification I group the range of evolved movement parameters into four categories or movement types. I then discuss how these movement types interact with current human-caused landscape changes, and how this often results in non-optimal movement. 3From this synthesis I develop a hypothesis that predicts the relative importance of the different population-level consequences of these non-optimal movements, for the four movement types. 4Populations of species that have inhabited landscapes with high habitat cover or patchy landscapes with low-risk matrix should have evolved low boundary responses and moderate to high movement probabilities. These species are predicted to be highly susceptible to increased movement mortality resulting from habitat loss and reduced matrix quality. 5In contrast, populations of species that evolved in patchy landscapes with high-risk matrix or dynamic patchy landscapes are predicted to be highly susceptible to decreased immigration and colonization success, due to the increasing patch isolation that results from habitat loss. 6Finally, I discuss three implications of this synthesis: (i) ,least cost path' analysis should not be used for land management decisions without data on actual movement paths and movement risks in the landscape; (ii) ,dispersal ability' is not simply an attribute of a species, but varies strongly with landscape structure such that the relative rankings of species' dispersal abilities can change following landscape alteration; and (iii) the assumption that more mobile species are more resilient to human-caused landscape change is not generally true, but depends on the structure of the landscape where the species evolved. [source] Improving the design and management of forest strips in human-dominated tropical landscapes: a field test on Amazonian dung beetlesJOURNAL OF APPLIED ECOLOGY, Issue 4 2010Jos Barlow Summary 1.,The future of tropical forest species depends in part on their ability to survive in human-modified landscapes. Forest strips present a priority area for biodiversity research because they are a common feature of many managed landscapes, are often afforded a high level of legal protection, and can provide a cost-effective and politically acceptable conservation strategy. 2.,Despite the potential conservation benefits that could be provided by forest strips, ecologists currently lack sufficient evidence to inform policy and guide their design and management. 3.,We used a quasi-experimental landscape in the Brazilian Amazon to test the importance of four management-relevant variables (forest type, isolation distance, forest structure, and large mammal activity) on the potential biodiversity conservation value of narrow forest strips for dung beetles. 4.,Information-theoretic model selection based on AICc revealed strong support for the influence of large mammal activity and forest type on dung beetle abundance; isolation distance on species richness; and forest structure on the relative abundance of matrix-tolerant species. Multi-dimensional scaling showed a strong influence of forest type and isolation on community composition and structure, with riparian and dry-land strips having complementary sets of species. 5.,Synthesis and applications. To enhance the conservation value and ecological integrity of forest strips in human-modified landscapes we recommend that strip design considers both isolation distance and whether or not the strips encompass perennial streams. In addition, we identify the maintenance of forest structure and the protection of large mammal populations as being crucially important for conserving forest dung beetle communities. [source] Using historical ecology to understand patterns of biodiversity in fragmented agricultural landscapesJOURNAL OF BIOGEOGRAPHY, Issue 11 2005Ian D. Lunt Abstract Aim, To enhance current attempts to understand biodiversity patterns by using an historical ecology approach to highlight the over-riding influence of land-use history in creating past, current and future patterns of biodiversity in fragmented agricultural landscapes. Methods, We develop an integrative conceptual framework for understanding spatial and temporal variations in landscape patterns in fragmented agricultural landscapes by presenting five postulates (hypotheses) which highlight the important role of historical, anthropogenic disturbance regimes. We then illustrate each of these postulates with examples drawn from fragmented woodlands in agricultural areas of south-eastern Australia, and discuss these findings in an international context. Location examples are drawn from agricultural areas in south-eastern Australia. Results, We conclude that there is limited potential to refine our understanding of patterns of biodiversity in human-modified landscapes based on traditional concepts of island biogeography, or simple assumptions of ongoing destruction and degradation. Instead, we propose that in agricultural landscapes that were largely cleared over a century ago: (1) present-day remnant vegetation patterns are not accidental, but are logically arrayed due to historic land-use decisions, (2) historic anthropogenic disturbances have a major influence on current ecosystem conditions and diversity patterns, and (3) the condition of remnant ecosystems is not necessarily deteriorating rapidly. Main conclusions, An historical ecology approach can enhance our understanding of why different species and ecosystem states occur where they do, and can explain internal variations in ecological conditions within remnant ecosystems, too often casually attributed to the ,mess of history'. This framework emphasizes temporal changes (both past and future) in biotic patterns and processes in fragmented agricultural landscapes. Integration of spatially and temporally explicit historical land-use information into ecological studies can prove extremely useful to test hypotheses of the effects of changes in landscape processes, and to enhance future research, restoration and conservation management activities. [source] Beyond Reserves: A Research Agenda for Conserving Biodiversity in Human-modified Tropical LandscapesBIOTROPICA, Issue 2 2009Robin L. Chazdon ABSTRACT To truly understand the current status of tropical diversity and to forecast future trends, we need to increase emphasis on the study of biodiversity in rural landscapes that are actively managed or modified by people. We present an integrated landscape approach to promote research in human-modified landscapes that includes the effects of landscape structure and dynamics on conservation of biodiversity, provision of ecosystem services, and sustainability of rural livelihoods. We propose research priorities encompassing three major areas: biodiversity, human,environment interactions, and restoration ecology. We highlight key areas where we lack knowledge and where additional understanding is most urgent for promoting conservation and sustaining rural livelihoods. Finally, we recommend participatory and multidisciplinary approaches in research and management. Lasting conservation efforts demand new alliances among conservation biologists, agroecologists, agronomists, farmers, indigenous peoples, rural social movements, foresters, social scientists, and land managers to collaborate in research, co-design conservation programs and policies, and manage human-modified landscapes in ways that enhance biodiversity conservation and promote sustainable livelihoods. [source] | ||||||||||